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authorLaurent Vivier <lvivier@redhat.com>2015-08-24 19:29:45 +0200
committerLaurent Vivier <lvivier@redhat.com>2015-09-25 14:52:17 +0200
commit9491e9bc019a365dfa9780f462984a0d052f4c0d (patch)
treea4d36d9ecda0e7f129ded20072e572bf9a141785 /hw
parent8a47d575dfac0f6675e2ac56c5921cc520d021a6 (diff)
i6300esb: remove muldiv64()
Originally, timers were ticks based, and it made sense to add ticks to current time to know when to trigger an alarm. But since commit: 7447545 change all other clock references to use nanosecond resolution accessors All timers use nanoseconds and we need to convert ticks to nanoseconds, by doing something like: y = muldiv64(x, get_ticks_per_sec(), PCI_FREQUENCY) where x is the number of device ticks and y the number of system ticks. y is used as nanoseconds in timer functions, it works because 1 tick is 1 nanosecond. (get_ticks_per_sec() is 10^9) But as PCI frequency is 33 MHz, we can also do: y = x * 30; /* 33 MHz PCI period is 30 ns */ Which is much more simple. This implies a 33.333333 MHz PCI frequency, but this is correct. Signed-off-by: Laurent Vivier <lvivier@redhat.com>
Diffstat (limited to 'hw')
-rw-r--r--hw/watchdog/wdt_i6300esb.c11
1 files changed, 3 insertions, 8 deletions
diff --git a/hw/watchdog/wdt_i6300esb.c b/hw/watchdog/wdt_i6300esb.c
index 3e07d44878..a91c8fdad0 100644
--- a/hw/watchdog/wdt_i6300esb.c
+++ b/hw/watchdog/wdt_i6300esb.c
@@ -129,14 +129,9 @@ static void i6300esb_restart_timer(I6300State *d, int stage)
else
timeout <<= 5;
- /* Get the timeout in units of ticks_per_sec.
- *
- * ticks_per_sec is typically 10^9 == 0x3B9ACA00 (30 bits), with
- * 20 bits of user supplied preload, and 15 bits of scale, the
- * multiply here can exceed 64-bits, before we divide by 33MHz, so
- * we use a higher-precision intermediate result.
- */
- timeout = muldiv64(timeout, get_ticks_per_sec(), 33000000);
+ /* Get the timeout in nanoseconds. */
+
+ timeout = timeout * 30; /* on a PCI bus, 1 tick is 30 ns*/
i6300esb_debug("stage %d, timeout %" PRIi64 "\n", d->stage, timeout);